Lithographic printing plates

ABSTRACT

A lithographic and offset printing plate comprising an aluminum support having thereon image areas comprising copper electroplated on a metallic silver image formed in openings of or on an anodic oxidation film corresponding to said image areas of said support is disclosed.

United States Patent 11 1 1111 3,841,218

Sakaki Oct. 15, 1974 15 1 LITHOGRAPIIIC PRINTING PLATES 1.605.082 11/1926 T1151 101 458 1.886.817 11/1932 Johnston 101/459 [751 Inventor: Sakak" OduwarHhi 3.223.524 12/1965 Konig 101/458 x J21Pan 3.378.372 4 1968 Vandeputtc c1111.... 101/456 x 3.556.952 1/1971 Fry 61111. 101 458 x [73] Asslgnee' 5: 11:23}: 2'15"" 3.669.018 6/1972 Whcclock 101/456 g p R1I.818 4/1900 R058" 101/459 [22] Filed: July 24, 1972 1 Primary Examiner-C1yde I. Coughenour 1 [21] Appl' NO" 274,383 Attorney, Agent, or FirmSughrue, Rothwell, Mion.

Zinn & Macpeak [30] Foreign Application Priority Data y 23, 1971 Japan 46-55015 [57] ABSTRACT [52] US. Cl. 101/459 101/456 A lithographic and Offset printing plate comprising an 151] 1111. c1...'.'.:.'...'.'.'I."I.'.'.'" "III IIII .8416 l/08 lu inum pport having thereon image area [58] Field of Search... iOl-/456 4 459 prising copper electroplated on a metallic silver image IIII u a formed in n gs of or on an anodic oxidation film References Cited corresponding to said image areas of said support i UNITED STATES PATENTS F 5 48,004 12/1903 Pancoast 101/459 8 Chi 3 Drawing Figures LITHOGRAPHIC PRINTING PLATES BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to lithographic and offset printing aluminum plates (including aluminium alloy plates) and particularly to lithographic and offset printing plates in which copper (copper plated on metallic silver) is utilized as the image part and an anodic oxidation film is utilized as the non-image part.

2. Description of the Prior Art It is known to produce a lithographic and offset printing plate by a method in which a printing element composed of a photo-sensitive resin (for example, a diazo resin, etc.) applied on a hydrophilic anodic oxidation film on a surface of an aluminum plate is subjected to a photo-engraving treatment to form a hydrophobic non-metal" image.

In this printing plate, the hydrophilic non-image part has the property that is repels inks and is wetted with water and the hydrophobic image part has the property that it accepts inks and repels water with these properties being utilized at printing.

Such a prior art photo-engraving printing plate has a serious disadvantage that it is lacking in abrasion resistance at printing, because the image part is non-metal.

On the other hand, a bimetal printing plate which is a printing plate having a metallic copper image on an aluminum plate is known. This plate is produced by a process which comprises plating copper on the entire surface of the aluminum plate, applying a photosensi tive layer thereto, exposing to light, developing to form an image on the coated layer, and dissolving selectively the non-image part using a solution which dissolves only the copper and not the aluminum to expose the aluminum surface and then dissolving and removing the coated layer of the image part to expose a metallic copper image on the aluminum plate.

Additionally, it is known the hydrophilic properties of the anodic oxidation film of the aluminum are superior to that of the aluminum and the abrasion resistance of the anodic oxidation film is superior to that of the aluminum too.

However, it is difficult andtroublesome to carry out uniform copper plating on the anodic oxidation film of aluminum having superior hydrophilic properties.

Thus, study and development on printing plateshaving a metal image (hydrophobic) on the anodic oxidation film of aluminum have become of great interest in the offset printing industry.

Accordingly, an object of the present invention is to provide lithographic and offset printing plates which posses the above-described characteristics and have excellent printing durability.

SUMMARY OF THE INVENTION The present invention has been attained by providing a printing plate in which electrically conductive metallic silver images are formed in the openings of and on the anodic oxidation film of the aluminum support and the metallic silver image is selectively electroplated with copper.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS FIG. 1 is a cross sectional view of an anodic oxidation film of aluminum containing silver halide, in which I is aluminum, 2 is the anodic oxidation film and 3 is the silver halide. 7

FIG. 2 is a cross sectional view of an intensified anodic oxidation film of aluminum after exposing, developing, fixing and rinsing, in which 4 shows an image part where silver particles connect each other by intensification.

FIG. 3 is a cross section where copper is plated on the image part of connected silver particles as in FIG. 2, in which 5 is deposited copper.

DETAILED DESCRIPTION OF THE INVENTION The printing plate of this invention can be produced as follows.

Namely, a photosensitive aluminum sheet in which a silver halide is incorporated in the openings of an anodic oxidation film formed on the aluminum [for example, Alphoto, (registered trademark), produced by the Fuji Photo Film Co., refer to US. Pat. No.

2,766,119] is exposed-to light, developed and fixed to produce a silver image. The thus resulting silver image, however, has no electric conductivity because the formed silver particles are isolated from each other and are not in electrical contact. Then the sheet is dipped in an aqueous reducing solution containing a silver salt (an intensifer) to deposit selectively metallic silver onv the image part, by which electric conduchundred thousands sheets of distinct prints can be produced therefrom.

Selective copper plating on the electrically conductive silver image part is carried out by connecting a copper plate to an anode and an aluminum sheet having the silver image to a cathode, and applying an electric current to a copper plating solution in an electroplating cell.

Namely, since the anodic oxidation film of the aluminum has a high electric insulating property, when an electric current is applied to the aluminum plate as the support in the copper plating solution after forming the silver image having good electric conductivity in openings of or on the anodic oxidation film, the electric current flows selectively through the parts having a lower resistivity (namely, the parts having good electric conductivity) and thus the copper is plated. The plated copper film is sufficient for practical use if the thickness thereof is about 0.5;1. to 2 or 3p. or so.

As an intensifier, (which generally comprises a silver ion source, a silver ion reducing agent, e.g., a photographic developer, a silver complexing agent such as thiosulfatc, thiocyanate, etc, a preservative such as sodium sulfite and a pH adjusting agent) which can be used in the present invention, a Metol type intensifier and a silver salt-hydroquinone type intensifier are generally used. In order to render the image part electrically conductive, it is generally sufficient to dip the plate in the metol type intensifier for approximately 40 minutes and in the silver salt hydroquinone type intensifier for approximately 20 minutes.

Suitable alloys of aluminum which can be employed are those of copper, magnesium or iron. A copper aluminum alloy is preferred in which the copper content ranges from 0.05 to 1 percent by weight, preferably from 0.12 to 0.3 percent by weight.

Any of the copper plating solutions generally used in copper plating are suitable, for example, those copper plating baths disclosed in U.S. Pat. Nos. 2,437,865 (pyrophosphoric acid baths), 2,707,166 (cupric sulfate baths) 2,873,234 (cupric cyanide baths), and Metal Finishing, Vol. 57, page 80 (1959) (cupric tetrafluoroborate baths).

The invention will now be described in greater detail by reference to the following examples which are given for the purposes of illustration and are not to be interpreted as limiting the invention.

EXAMPLE 1 Now referring in detail to FIGS. 1 to 3, a photosensitive aluminum plate which contained silver halide in the openings of an anodic oxidation film formed on an aluminum support in an oxalic acid electrolyte (Alphoto above-described) was imagewise exposed to light, developed and fixed in the following compositions and rinsed to form a metallic silver image.

Developer Composition Ethylene Diamine 0.6 g Anhydrous Sodium Sulfite 80 g Hydroquinone 20 g l Phenyl-3-pyrazolidone 2 g Sodium Thiosu|fate'5H,O 60 g Potassium Bromide l g Potassium Thiocyanate l g Sodium Hydroxide l g Water to make 1 liter Developing time: 2 seconds Fixing Solution Composition:

Monosodium Phosphate 20 g Ammonium Thiosulfate 150 g Potassium Pyrosulfite 50 g Ammonium Thiocyanate 50 g Water to make I liter Fixing time: 5 seconds.

The plate was then dipped in an intensifier having the following composition for 30 60 minutes to render the image electrically conductive.

AgNO 60 g Na SO 60 g Na S O -5H,O 90 105 g Na CO g Metol 25 g Water 6 liters Further, a portion of the plate was dipped in a 10 percent aqueous sodium hydroxide solution for 3 minutes to dissolve and remove a part of the anodic oxidation film which was unnecessary as the printing plate. After EXAMPLE 2 After dipping an Alphoto plate on which an image was formed in the same manner as described in Example l in an intensifier having the following composition for 30 60 minutes, it was subjected to copper plating in a pyrophosphoric acid plating bath to produce a printing plate.

AgNO 60 g NaI SO g Na,S O=,-5H O I05 g Metal 25 g Water 6 liters EXAMPLE 3 A printing plate was produced in the same manner as described in Example 1 but an intensifier having the following composition was used.

A No, 91.5 g Na SO 25 g Na S O -5l-l O I60 g Hydroquinone 25 g NH SCN g Water 3 liters EXAMPLE 4 A printing plate was produced in the same manner as described in Example 1 but an intensifier having the following composition was used.

AgNO 60 g N21 50: 75 g Na S O -5H O I05 g Metol 25 g CuSO, 0.2 g Water 6 liters While the invention has been described in detail and in terms of specific embodiments thereof, it will be apparent to one skilled in the an that various changes and modifications can be made therein without departing from the spiritand scope thereof.

I claim:

1. A lithographic and offset printing plate comprismg:

a. an aluminum support:

b. a substantially non-conducting porous anodic oxidation film of aluminum on said support;

0. an electrically conductive intensified silver image formed on and in the pores of a portion of said oxidation film; and

d. a copper image formed on said intensified silver image and in correspondence thereto, said printing plate thus presenting ink repellant areas of said anodic oxidation film and an ink attractive copper image.

2. The plate of claim 1 consisting essentially of said aluminum support covered by said anodic oxidation film, said anodic oxidation film carrying said image areas of copper on said metallic silver, the areas of said anodic oxidation film not covered by said image areas of copper on said metallic silver being ink repellant to form non-printing areas and said image areas of copper on said metallic silver being ink-attractive to form printing areas.

3. The plate of claim 1 wherein said copper is in the form of a film having a thickness of about 0.5 microns to 3 microns.

4. The plate of claim 3 wherein said copper has a 

1. A LITHOGRAPHIC AND OFFSET PRINTING PLATE COMPRISING: A. AN ALUMINUM SUPPORT: B. A SUBSTANTIALLY NON-CONDUCTING POROUS ANODIC OXIDATION FILM OF ALUMINUM ON SAID SUPPORT; C. AN ELECTRICALY CONDUCTIVE INTENSIFIED SILVER IMAGE FORMED ON AND IN THE PORES OF A PORTION OF SAID OXIDATION FILM; AND D. A COPPER IMAGE FORMED ON SAID PRINTING THE PLATE THUS AND IN CORRESPONDENE THERETO, SAID PRINTING PLATE THUS PRESENTING INK REPELLANT AREAS OF SAID ANODIC OXIDATION FILM AND AN INK ATTRACTIVE COPPER IMAGE.
 2. The plate of claim 1 consisting essentially of said aluminum support covered by said anodic oxidation film, said anodic oxidation film carrying said image areas of copper on said metallic silver, the areas of said anodic oxidation film not covered by said image areas of copper on said metallic silver being ink repellant to form non-printing areas and said image areas of copper on said metallic silver being ink-attractive to form printing areas.
 3. The plate of claim 1 wherein said copper is in the form of a film having a thickness of about 0.5 microns to 3 microns.
 4. The plate of claim 3 wherein said copper has a thickness of about 0.5 to 2 microns.
 5. The plate of claim 1 wherein said aluminum is alloyed with copper, magnesium or iron.
 6. The plate of claim 5 wherein said aluminum is alloyed with 0.05 to 1 percent by weight copper.
 7. The plate of claim 1 wherein said anodic oxidation film is integral with said aluminum support, being an aluminum oxidation product.
 8. The plate of claim 1 wherein the copper is electroplated. 